Which compound listed below will dissolve in water?
A) CCl4
B) SiO2
C) NH3
D) all of the compounds
E) none of the compounds
The correct Answer and Explanation is:
The correct answer is C) NH3 (Ammonia).
Here’s an explanation for why NH3 dissolves in water, while the other compounds do not:
- Ammonia (NH3): Ammonia is a polar molecule with a lone pair of electrons on the nitrogen atom, which makes it capable of forming hydrogen bonds with water molecules. This polarity and hydrogen-bonding capability allow ammonia to readily dissolve in water. When ammonia dissolves, it partially ionizes into ammonium (NH4⁺) and hydroxide (OH⁻) ions, creating a basic solution. The interaction between ammonia molecules and water molecules is strong enough to overcome the forces holding the ammonia molecules together, leading to dissolution.
- Carbon Tetrachloride (CCl4): CCl4 is a nonpolar molecule. Nonpolar molecules typically do not dissolve in polar solvents like water because they cannot form favorable interactions with the water molecules. The intermolecular forces between water molecules (hydrogen bonds) are much stronger than the forces between water and CCl4 molecules. Therefore, CCl4 does not dissolve in water.
- Silicon Dioxide (SiO2): SiO2, or silica, is a network solid with a very strong covalent bond structure, which makes it insoluble in water. Water molecules cannot break the strong covalent bonds between the silicon and oxygen atoms in the SiO2 structure. Silica is only soluble in highly basic or acidic solutions, not in water.
- None of the compounds (Option E): This option is incorrect because ammonia (NH3) is soluble in water.
In conclusion, ammonia (NH3) is the only compound among the options that can dissolve in water due to its polarity and ability to form hydrogen bonds with water molecules.